Add support for the Dylan language to ClangASTContext

[housel]

Summary

This change adds eLanguageTypeDylan to the set of languages supported
by ClangASTContext. Debug info generated by the Open Dylan compiler's
LLVM back-end was designed to be compatible with C debug info.

[aprantl]

source/Symbol/ClangASTContext.cpp

123

Please add a comment explaining that "The Debug info generated by the Open Dylan compiler's
LLVM back-end was designed to be compatible with C debug info."

[housel]

Adds an inline comment about Open Dylan debug info

[housel]

I don't have commit access; could someone land this please? Thanks.

[brucem]

I can land this today.

[housel]

Updated against r347619

source/Symbol/ClangASTContext.cpp

return language == eLanguageTypeUnknown || // Clang is the default type system
          Language::LanguageIsC(language) ||
          Language::LanguageIsCPlusPlus(language) ||
          Language::LanguageIsObjC(language) ||
          Language::LanguageIsPascal(language) ||
          // Use Clang for Rust until there is a proper language plugin for it
          language == eLanguageTypeRust ||
          language == eLanguageTypeExtRenderScript ||
          // Use Clang for D until there is a proper language plugin for it
-         language == eLanguageTypeD;
+         language == eLanguageTypeD ||
+         // Open Dylan compiler debug info is designed to be Clang-compatible
+         language == eLanguageTypeDylan;
 }
 
 // Checks whether m1 is an overload of m2 (as opposed to an override). This is
 // called by addOverridesForMethod to distinguish overrides (which share a
 // vtable entry) from overloads (which require distinct entries).
 bool isOverload(clang::CXXMethodDecl *m1, clang::CXXMethodDecl *m2) {
   // FIXME: This should detect covariant return types, but currently doesn't.
   lldbassert(&m1->getASTContext() == &m2->getASTContext() &&